Overriding method_added on a refinement's anonymous module can cause the opt_* opcodes to behave incorrectly

Ruby stores flags in (({ruby_vm_redefined_flag})) to track whether certain methods have been redefined on particular classes. If the redefined flag for a certain class and operator is not set, Ruby will skip method lookup and directly call the method implementing that operator.

The current implementation of refinements uses the (({method_added})) callback to set these flags. If this method is overridden, the flags are not set properly.

This code should raise a RuntimeError with the message "addition is not allowed". Instead it outputs "3". If line 3 is removed, it behaves correctly.